Microsoft has what’s probably the largest deployment of OMA and Exchange ActiveSync. What have they learned about how to scale and provision these services?
Quite a bit, as it turns out. See this whitepaper for the details. Basically, they provide OMA, OWA, and EAS service for 50,000 users using two Exchange 2003 front-ends and their associated back-end mailbox servers. The paper doesn’t provide any real performance data, but it does mention that you can do your own stress and scalability tests with ESP— always a good idea.
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Exchange Active Sync (EAS)